Ko Young-tae's office, located in the building on the right, is next to Choi Soon-sil's residence in the other building. Both buildings are owned by Choi. Ko is suspected of managing The Blue K and Wide Sports. Ko underwent 40 hours of questioning by prosecutors until Saturday as he had voluntarily appeared at the prosecution's office late Thursday after entering the country earlier that day. No details have been released yet. / Korea Times photo by Bae Woo-han

By Chung Hyun-chae

Ko Young-tae

The investigation by the prosecution on the influence-peddling scandal surrounding Choi Soon-sil, President Park Geun-hye's confidant, shed light on Choi's clandestine relationship with a host bar worker.

Ko Young-tae, 40, had voluntarily turned up at the prosecutor's office for questioning late Thursday after entering the country earlier in the day. After a 40-hour prosecutorial investigation over how confidential documents including the President's speeches reached Choi, he returned home around noon Saturday but was summoned again Sunday.

No details about the interrogation are available.

Ko is suspected of managing The Blue K and Widec Sports _ paper companies Choi set up in Korea and Germany allegedly to funnel money away from the Mir and K-Sports foundations.

Little is known about Ko.

He is a former member of the national saber team, winning a gold medal at the 1998 Asian Games in Bangkok.

Being through with sports, Ko worked at well-known host bars in Gangnam, southern Seoul, according to reports and witnesses. A host bar is an establishment where female customers are served by male hosts who engage in conversation as well as sometimes barter for sexual services. The two are believed to have met and become close at one such host bar, around 2006.

"Ko made a lot of money with his good looks," said an anonymous man who introduced himself as Ko's coworker at the bar during Kim Hyun-jung's "NEWS SHOW" on Christian Broadcasting Service (CBS) Radio, Friday.

"I assume that Choi was one of Ko's close customers as they are on friendly terms with each other despite the 20-year age gap between them," he said. Choi is 60 years old, and the friendly terms despite a two-decade age difference can indicate an intimate relationship, according to reports.

According to the coworker, Ko was working as a sales director, tasked to bring in rich middle-aged women to the bar using the alias Min-woo.

Having a foot in the fashion industry in 2008 with Choi's assistance, Ko launched his accessory brand Villomillo. It became famous after President Park carried his bag in 2013. With the instant success, his products drew a lot of celebrity customers and he established a wide range of contacts.

Cha Eun-taek, another embattled man in charge of Mir Foundation, was Ko's acquaintance, and Ko introduced Cha to Choi, which marked the turning point of their relationship from good to sour, according to news reports.

"Choi's favorite thing to do is to edit presidential speeches," Ko said during an interview with broadcaster JTBC in the middle of this month.

That comment prompted the cable news channel to look for the President's speeches in computer files. The JTBC finally found the files and that turned out to be one of the biggest breaking stories in recent years.

This backfired on Choi when she said the tablet computer's owner is Ko, not her. "I do not even know how to use a tablet PC," Choi said during an interview with the Segye Ilbo on Wednesday in Germany.